In einem idyllischen Vorort verschwindet im Jahr 2008 der vierjährige Junge Callum Reid. Während seine Eltern Claire und Daniel zunächst ein bloßes Versteckspiel des lebhaften Kindes vermuten, findet die Polizei kurze Zeit später dessen heißgeliebten Roller und der Verdacht wird zur traurigen Gewissheit: Callum wurde offenbar entführt. Am Abend zuvor wurde noch bei einem gemeinsamen Grillfest unter Nachbarn fröhlich getanzt und getrunken, bis die Stimmung plötzlich umschlug und in einer eifersüchtigen Schlägerei unter den Männern endete. Erst am nächsten Morgen stellte Claire erschrocken fest, dass Callum nicht in seinem Bettchen war. Fünf Jahre später findet man die Leiche von Callum nicht weit von seinem Elternhaus entfernt. Die Polizistin Maggie Brand rollt daraufhin den Fall neu auf. Die Ermittlerin, die schon damals in den Fall involviert war, sucht verzweifelt nach neuen Hinweisen – und tatsächlich tun sich einige Ungereimtheiten auf. Zudem scheint langsam Licht ins Dunkel zu kommen, was am Abend vor Callums Verschwinden wirklich passiert ist. Maggie befragt noch einmal die Familie Reid, ihr damaliges Au-Pair-Mädchen Nina Huber und die Nachbarschaft. Ist der Mörder etwa unter ihnen? Der Fall selbst geht Maggie dabei näher als erwartet: War sie vor fünf Jahren noch hochschwanger, ist sie mittlerweile selbst Mutter eines Jungen. Doch nicht nur die Arbeit an dem Fall macht Maggie zu schaffen, auch privat muss die junge Frau einiges einstecken.
As Maggie and her team dig deeper into Callum Reid’s disappearance, they re-interview the Reids and their neighbours, forcing them to reopen old wounds and revisit painful memories, as they find themselves once again under suspicion. When new evidence eliminates the original prime suspect, the holes and inconsistencies in the first investigation begin to emerge and Maggie becomes convinced that Nina Huber, the Reids’ former au-pair, could hold the key. But where is she? And why can no-one find her? Meanwhile Maggie has to process some disturbing news about her own son, Sam, causing increasing tension at home as she struggles to remain focused on the case. The Reids find their coping mechanisms in conflict as Claire’s drive to find her child’s killer threatens her relationship with their remaining son. Meanwhile, we revisit the events surrounding the night of the barbecue, gradually uncovering the truth about Nina’s relationship, the secret lover the Reids’ neighbour Teresa cannot reveal and the fears that haunt young Luke’s nightmares. When a trip to Germany leads to a shocking revelation, Maggie is forced to accept that they may have been wrong about the time and even the location of Callum’s disappearance. Then Claire makes a disturbing discovery closer to home and Daniel finds himself under growing suspicion. But who is the man who’s been watching the Reids’ house? And why is he so interested in Maggie? Maggie brings Daniel in for questioning, but the secret she uncovers is not what she was expecting. Frustrated by the case and concerned for her son, a distracted Maggie unwittingly places herself in danger and is stunned when a stranger confronts her with an unexpected confession.
Under pressure to charge her prime suspect, Maggie’s still not convinced they’ve found the killer. However, she’s taken aback to discover that her stalker had close links to the Reid family. Meanwhile, Theresa’s return pushes Claire and Daniel’s marriage to breaking point and Luke is shaken by the reappearance of a teenage neighbour, who seems intent on making amends for the past. As pressure grows to go public with the arrest, Maggie finds herself increasingly isolated at work and home as she confronts the reality that her son isn’t like the other children in his class. When her suspect reveals information that only the killer could have known, Maggie has no choice but to charge them. But when a conflicted Teresa reignites Maggie’s suspicions about Daniel, Maggie begins to piece together Callum’s final hours, finding her instinct as a mother at war with her desire to solve the crime, as she comes to understand that that death isn’t always the hardest loss to bear. Then a brutal death effectively closes the case and Maggie faces a stark choice – will she protect her career or expose the truth? As the final pieces of the puzzle fall into place, we finally learn how and why Callum Reid died and how a terrible misunderstanding spiraled into a lie that destroyed a whole community.